Silicone gel compositions have been widely used as sealants and fillers for electrical or electronic parts because they can form silicone gels having good stress relaxation, electrical characteristics, heat resistance and weather resistance by curing (refer to Patent Documents 1 to 3). Examples of such silicone gel compositions include a silicone gel composition comprising an organopolysiloxane containing vinyl groups, having a branched structure and having viscosity of from 10 to 10,000 centistokes at 25 C., a linear organopolysiloxane containing hydrogen atoms bonded to silicon atoms, and a hydrosilylation reaction catalyst (refer to Patent Document 4); a silicone gel composition comprising an organopolysiloxane containing vinyl groups having a branched structure, an organopolysiloxane containing hydrogen atoms bonded to silicon atoms, and a hydrosilylation reaction catalyst (refer to Patent Document 5); and a silicone gel composition comprising an organopolysiloxane containing vinyl groups, having a branched structure and having a viscosity of from 20 to 10,000 centistokes at 25 C., a linear organopolysiloxane capped by vinyl groups at both ends of its molecular chain, a linear organopolysiloxane containing hydrogen atoms bonded to silicon atoms only at both ends of its molecular chain, and a hydrosilylation reaction catalyst (refer to Patent Document 6).
On the other hand, the present inventors proposed that a silicone gel composition for sealing or filling of electrical or electronic parts which suppresses the occurrence of air bubbles and cracks in silicone gel can be provided and that an electrical or electronic part having excellent reliability can be provided by using a silicone gel composition which, by curing, forms a silicone gel having, at 25 C. and a shear frequency of 0.1 Hz, a loss elastic modulus of from 1.0×103 to 1.0×105 dyne/cm2 and a complex elastic modulus of 1.0×106 dyne/cm2 or less, and, advantageously, having 1/4 consistency of from 30 to 80 (refer to Patent Document 7, especially Practical Example 5). Similarly, it has been proposed that the occurrence of air bubbles, cracks and interface debonding can be prevented and operational reliability of a semiconductor device can be assured, even when heat cycling or vibration is applied to the semiconductor device, by using a silicone resin having a certain penetration and, advantageously, having a loss elastic modulus adjusted to 17% or greater of the storage elastic modulus (refer to Patent Document 8).